Semi-finished products or sheet metal blanks, in particular tailored blanks, are used in the manufacture of motor vehicles, in particular in the manufacture of bodywork components for motor vehicles. On account of different demands placed on these sheet metal blanks, tailored blanks are frequently composed of a plurality of metal sheets of differing thickness that are firmly bonded to one another, generally welded. Many applications of sheet metal blanks require a sheet metal blank to have homogeneous transitions between metal sheets of differing thickness. On the one hand, this is required in order to design load curves of the components without force jumps or spontaneous malfunction behaviour. Furthermore, a zone of homogeneous transition from one metal sheet thickness to the other is desirable in order to ensure better flowing and increased degrees of deformation during subsequent forming processes. Furthermore, joining-together of connecting edges of differing thicknesses by means of laser welding is problematic.
What is known as flexible rolling is known in the art for producing homogeneous sheet metal transitions between different sheet metal thicknesses. In this method, homogeneous transition zones are introduced into the metal sheets or strips by flexible rolling. However, this method has the drawback that only linear regions of the sheet metal blank can be altered in their thickness, so that non-linear transition zones are not possible. Furthermore, the transitions can be configured only in a relatively long-wave manner. For example, it is possible to produce only homogeneous transitions of 50 mm and more.
Another method according to the prior art in which different materials can also be used is known from DE 10 2004 035 887 A1. In this method, the thicker metal sheet is firstly rolled to a desired thickness dimension in the region of the connecting edge. Subsequently, the metal sheets can then be welded to one another.
However, this method has the problem that a specific roll stand or a specific rolling device is necessary. Moreover, apart from the additional special device, an additional operation and a longer manufacturing time, with correspondingly higher costs, are required. In addition, the method according to DE 10 2004 035 887 A1 may be used only for producing a linear connecting edge course. Moreover, after the rolling and prior to the connecting of the metal sheets, the rolled metal sheet still has to be trimmed, so that a further operation is necessary.